The present invention relates generally to an air processing system and more particularly to a control, operating in conjunction with a thermostat and a two-speed compressor, for controlling the relative humidity in an enclosure.
Air processing systems including a thermostat and a two-speed compressor are well known. The compressor may be part of a conventional air conditioner or heat pump. The compressor is cycled ON and OFF and between a LOW and HIGH speed in accordance with the temperature of the enclosure and the thermostatic demand signals, as is well known. HIGH speed operation typically results when the enclosure temperature exceeds the set temperature of the thermostat by an incremental temperature, such as 2.degree. F.
Processed air is delivered to the enclosure by a blower. With a heat pump, the blower typically has two speeds and operates at HIGH speed during cooling and LOW speed during heating, regardless of compressor speed.
The presently available cooling mode humidity controls for incorporation into these types of air processing systems are electromechanical monitors designed solely to control blower speed. Whenever relative humidity of the enclosure exceeds the set point of an electromechanical humidistat, LOW blower speed is maintained. Slower air movement increases dehumidification in the area of the "cold" inside compressor coil.
These electromechanical humidity monitors are inefficient and inexact. While humidity reduction is generally enhanced, the temperature of the enclosure is often not preserved, leading to higher energy costs. Additionally, the relative humidity tolerance of such monitors is much too great to provide adequate control for proper comfort.